-LRB- CNN -RRB- -- Former U.S. Sen. Arlen Specter , who embodied a vanishing breed of liberal Republicanism before switching to the Democratic Party at the twilight of his political career , died Sunday after a long battle with cancer , his family announced .

Specter died of complications from non-Hodgkin 's lymphoma at his home in Philadelphia , his family said . He was 82 .

The veteran Pennsylvania politician had overcome numerous serious illnesses over the past two decades , including a brain tumor . He had been in the public eye since serving as a member of the Warren Commission , which investigated the assassination of President John F. Kennedy .

Specter was elected to the Senate in 1980 and represented Pennsylvania for 30 years , longer than anyone in the state 's history . His politically moderate image fit hand-in-glove in the politically blue Northeast , both with its Democratic centrists and its liberal Republicans .

He was also one of America 's most prominent Jewish politicians , a rare Republican in a category dominated by Democrats over the decades . And his name is synonymous with Pennsylvania , an idiosyncratic state that pushes and pulls between the two parties , and his home , the staunchly Democratic city of Philadelphia .

In 2006 , Philadelphia magazine called him `` one of the few true wild cards of Washington politics ... reviled by those on both the right and the left . ''

`` Charming and churlish , brilliant and pedantic , he can be fiercely independent , entertainingly eccentric and simply maddening , '' the profile read .

Former Gov. Ed Rendell , a Democrat , called Specter `` a mentor , colleague and a political institution '' who `` did more for the people of Pennsylvania over his more than 30-year career with the possible exception of Benjamin Franklin . '' And Pat Toomey , the Republican who now holds Specter 's old Senate seat , praised him as `` a man of sharp intelligence and dogged determination . ''

And at the White House , President Barack Obama said Specter `` was always a fighter . ''

`` From his days stamping out corruption as a prosecutor in Philadelphia to his three decades of service in the Senate , Arlen was fiercely independent -- never putting party or ideology ahead of the people he was chosen to serve , '' Obama said in a written statement on Specter 's death .

And Vice President Joe Biden lamented the loss of `` my friend , '' `` who never walked away from his principles and was at his best when they were challenged . '' Biden will travel to Penn Valley , Pennsylvania , on Tuesday for Specter 's funeral , according to the White House .

G. Terry Madonna , director of the Franklin & Marshall College Poll and professor of pubic affairs at Franklin & Marshall College , said Frank Sinatra 's song `` My Way '' could apply to Specter .

`` There is n't any doubt in many respects he was an unusual politician , '' Madonna said . `` He did n't look at polls . He did n't track how his comments were playing out in the press . ...

`` He was fundamentally a pragmatist who could bend with the times , '' Madonna said , and he believed greatly that government could help people .

`` The Republicanism in his day , it was a different kind of Republican . He was a Philadelphian , and not into that staunchly conservative Republicanism that we see '' today .

Readers wished the best for Specter

Madonna called Specter an `` indefatigable '' public figure , highly demanding of both himself and those who worked for him over the years . He had a few election losses but he was undeterred by defeat , the prospects of losing and the challenges he faced .

`` The last thing you would have thought about Arlen Specter was that he was born in Kansas , '' Madonna said . `` He always came across as kind of urbane . He had a kind of caustic sense of humor . ''

But Specter in fact was born in Wichita , the youngest child of Lillie Shanin and Harry Specter , an immigrant from Ukraine . He grew up in Russell , Kansas , also the hometown of another Republican icon , a one-time presidential nominee and senator , Bob Dole .

After graduating from Russell High School in 1947 , Specter first went to the University of Oklahoma . But he eventually went east for his higher education . He earned a bachelor 's degree in international relations in 1951 from the University of Pennsylvania , in Philadelphia , where he graduated Phi Beta Kappa .

He was in the U.S. Air Force during the Korean War from 1951 to 1953 , serving as a second lieutenant in the Air Force Office of Special Investigations . He returned to his studies and graduated from Yale Law School in 1956 .

After Yale , he started practicing law and became an assistant district attorney in Philadelphia .

He served on the Warren Commission at the recommendation of Rep. Gerald Ford , later president . Specter is credited with co-authoring the `` single bullet theory , '' which suggested that some of the wounds to Kennedy and then-Texas Gov. John Connally were caused by the same bullet .

Even though he was a registered Democrat , Specter ran successfully for Philadelphia district attorney on the Republican ticket in 1965 and eventually registered as a Republican . He lost an election for Philadelphia mayor in 1967 .

He served as district attorney until 1974 and prosecuted corruption cases against Philadelphia magistrates and Teamsters .

Specter ran for the U.S. Senate in 1976 , but he was defeated in the Republican primary by John Heinz . He ran for governor but was defeated by Dick Thornburgh in the primary .

But he won his bid for Senate in 1980 and distinguished himself , serving until 2011 .

`` During his tenure in the Senate , Specter championed Pennsylvania 's economy and took an active interest in foreign affairs , meeting with dozens of world leaders as well as supporting appropriations to fight the global HIV/AIDS pandemic and backing free trade agreements between the U.S. and under-developed countries , '' according to a bio from the University of Pennsylvania Law School .

He served on the Senate Judiciary Committee , of which he was chairman from 2005 to 2007 . He served as chairman of the Senate Select Committee on Intelligence from 1995 to 1997 . And he was a senior member of the Senate Appropriations Committee .

Specter brought more financial resources to Pennsylvania than anyone in the state , working with mayors and other local leaders to help them get grants and aid , Madonna said . And he 's remembered across the state 's 67 counties for his efforts .

`` He did n't shy away from pork , '' Madonna said .

He participated in the confirmation hearings of 14 U.S. Supreme Court nominees , the Penn bio says . He is remembered for leading the charge against conservative nominee Robert Bork and going after Anita Hill , who accused nominee Clarence Thomas of harassment .

`` No member of Congress shaped the Supreme Court more than he did , '' Madonna said . `` He had a prosecutorial mindset . He could be incredibly persuasive as an interrogator . ''

Specter straddled right and left . He criticized Republicans for President Bill Clinton 's impeachment and voted in favor of the Iraq war . He supported embryonic stem cell research .

During the 1990s , he briefly announced a run for president but eventually dropped the effort and endorsed Bob Dole .

Despite his longtime membership in the Republican Party , Specter became more alienated from the party as it grew more conservative .

Like many of his moderate compatriots , he came to be viewed by the new conservatives as a RINO -- a Republican in Name Only . Decades after he switched to the Republican Party , he changed his stripes again . He became a Democrat in 2009 , saying Republicans had moved too far to the right and embraced social conservatism .

The move gave Democrats a 60-seat filibuster-proof majority in the Senate . But in 2010 , when he ran for re-election , Specter lost the Democratic primary to Rep. Joe Sestak .

Sestak , who went on to lose the race to Toomey , praised Specter via Twitter as `` a warrior of inestimable public service . ''

After the loss , Specter moved from the halls of Congress to those of academia , taking on a new role at the University of Pennsylvania Law School as an adjunct professor .

`` Arlen 's knowledge of the inner workings of the government and lawmaking is second to none , '' said Michael Fitts , the law school 's dean . `` The insight he brings from his career in public service , particularly as a leader on judicial issues , will be invaluable to our students as they prepare for their own careers in the law . ''

The senator practiced law when he was n't in office and authored books throughout his career , including :

-- `` Passion for Truth : From Finding JFK 's Single Bullet to Questioning Anita Hill to Impeaching Clinton ''

-- `` Never Give In : Battling Cancer in the Senate ''

-- `` Life Among the Cannibals : A Political Career , a Tea Party Uprising , and the End of Governing As We Know It ''

`` For the past quarter-century , he 's also been a Zelig-like national figure , '' the Philadelphia magazine article said , referring to the Woody Allen character from the film of the same name who changed his persona as his surroundings and circumstances changed .

`` From his role in sinking Robert Bork 's Supreme Court nomination to his cross-examination of Anita Hill , from stem-cell research to the impeachment of Bill Clinton , Specter 's greatest talent may be his unique ability to put himself -- somehow , some way -- in the center of the nation 's most important debates , '' the article said .

Obituaries 2012 : The lives they 've lived

CNN 's Sarah Hoye in Philadelphia contributed to this report .

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NEW : Vice President Joe Biden praises `` my friend , '' plans to attend funeral Tuesday

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Specter died of complications from non-Hodgkin 's lymphoma

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He represented Pennsylvania in the Senate longer than anyone else

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He was long one of the most prominent Jewish-American politicians